Common Sense Of Seal Selection Mechanical Seals

- Jun 03, 2019-

Seal selection must take into account operating conditions in order to select the appropriate seal form as well as the material, installation structure. Conditions to consider generally include: temperature, pressure, medium. 

Others also need to combine the characteristics of the equipment itself to consider the selection. About temperature, such as NBR material operating temperature range is generally -40 to 120 degrees C. That's more than 120 degrees C to consider the use of FKM, or even PTFE material. 

Low temperature is relatively rare, generally speaking in the case of -20 to -40 degrees C to consider the use of cold-resistant NBR, the general NBR material in low temperature environment will lead to the material hardening, resulting in leakage, such as railway locomotives in the northern winter often occur such problems. As for pressure, it affects the form of the seal to be selected. Generally speaking, low pressure medium pressure selection rubber or PU seal will not have too much problem. But to consider a shock pressure problem, such as the start in the construction machinery, when the impact pressure is much greater than the normal working pressure, so will often choose pressure up to 70MPA anti-shock squeeze gap HBY or SPGW as the main seal. 

PTFE combination seals are also a common choice. The problem with the media is simple. There are just special minor problems to be aware of, such as the frequent use of water-glycol and phosphate hydraulic oils in cylinders in the metallurgical industry. 

Sometimes although the operating temperature is not high, but the choice of materials is still very careful, hydraulic oil when using the latter or choose FKM. Seal selection is important, or must be selected in the light of the equipment itself. For example, the need for responsive, precise control of course choose the Steffen Grey Circle. Need high reliability, often choose Hanger's GD1000K series or NOK's SPGW. 

For example, the field work of the engineering machinery work often has shock and low temperature weather, its dust ring will choose exposed metal skeleton to avoid causing shedding. 

The seals of cylinders, compressor piston rings, high-pressure oil seals, and oil pumps in various scientific instruments require special structures to meet the requirements. 

All of these, all, welcome you and I to exchange seal selection 

What is common sense about mechanical seals? Mechanical seals are one of the mechanical basic components with more complex structures, and are the key components of various pumps, reaction synths, turbine compressors, submersible motors and other equipment. 

Its sealing performance and service life depend on many factors, such as selection, machine accuracy, proper installation and use. 

First, selection method 

Mechanical sealaccordingness according to the operating conditions and the nature of the medium, there are high temperature, low temperature mechanical seal, high pressure, corrosion-resistant mechanical seal, particle-resistant media mechanical seal and mechanical seal adapted to vaporize lightweight hydrocarbon media, etc. , should be different use of different structure types and materials of mechanical sealing. 

The main parameters of the selection are: sealing cavity pressure (MPA), fluid temperature (C), operating speed (M/S), fluid characteristics and effective space for sealing. 

There is no common sense in mechanical seals, and the basic principles of selection are: 

1, according to the sealing cavity pressure, to determine the sealing structure using balanced or non-balanced type, single-ended or double-ended surface. 

2, according to the working speed, determine the use of rotary or static, fluid pressure or non-contact type. 3, according to the temperature and fluid nature, determine the friction sub- and auxiliary sealing materials, as well as the correct selection of lubrication, flushing, insulation, cooling and other mechanical sealing cycle protection system.